Patterned epitaxial regrowth using overlapping pulsed irradiation

Abstract

A technique isdescribed for removing defects and disorder from crystalline layers and the epitaxial regrowth of such layers. The technique involves depositing short term bursts of energy over a limited spatial region of a material thereby annealing the otherwise damaged material and causing it to epitaxially regrow. Subsequent to the short term energy deposition, similar processing is sequentially effected on adjoining and overlapping regions such that a pattern is ultimately "written". This pattern forms a continuous region of essentially single crystal material.

We claim: 
     
       1. A method comprising irradiating a first region of material, which adjoins a single crystal material, with a pulse of energy which is absorbed at least in part by the material; and   irradiating subsequently a second region of material adjacent to the first region; the invention characterized in that the irradiated regions overlap each other sufficiently, and the energy of the irradiating pulse and the absorptivity of the irradiated material are of such values that each region of the material which is irradiated is seeded by adjacent single crystal material and is epitaxially regrown to an essentially single crystal structure, thereby defining an essentially continuous single crystal pattern.   
     
     
       2. The method of claim 1 wherein at least a portion of the irradiated material is disordered. 
     
     
       3. The method of claim 2 wherein the disordered material is rendered molten upon irradiation. 
     
     
       4. The method of claims 1 or 2 wherein the disordered material and a portion of the adjacent single crystal material is rendered molten upon irradiation, and regrows to an essentially single crystal by liquid epitaxial regrowth. 
     
     
       5. The method of claim 3 wherein the disordered material and a portion of the adjacent single crystal material is rendered molten upon irradiation, and regrows to an essentially single crystal by liquid epitaxial regrowth. 
     
     
       6. The method of claim 2 wherein the disordered material is disordered during ion implantation. 
     
     
       7. The method of claim 6 wherein the disordered material and a portion of the adjacent single crystal material is rendered molten upon irradiation, and regrows to an essentially single crystal by liquid epitaxial regrowth. 
     
     
       8. The method of claim 2 wherein the disordered layer is amorphous. 
     
     
       9. The method of claim 8 wherein amorphous layer is deposited. 
     
     
       10. The method of claim 2 wherein the disordered layer is polycrystalline. 
     
     
       11. The method of claim 3 wherein at least part of the irradiated material is semiconductor material. 
     
     
       12. The method of claim 11 wherein the semiconductor material is selected from the group consisting of silicon, germanium, gallium arsenide, and gallium phosphide. 
     
     
       13. The method of claim 11 wherein the disordered material differs in either composition or crystal configuration from the adjacent single crystal material, and heteroopitaxially regrows upon irradiation. 
     
     
       14. The method of claim 13 wherein the disordered material is silicon and the single crystal material is sapphire. 
     
     
       15. The method of claim 1 wherein the irradiated material comprises a dopant material which diffuses through at least part of the underlying material, and the underlying material, upon annealing, regrows to an essentially single crystal material doped with the dopant. 
     
     
       16. The method of claim 15 wherein prior to irradiation at least part of the material underlying the dopant layer is disordered. 
     
     
       17. The method of claim 15 wherein prior to irradiation essentially all of the material underlying the dopant layer is single crystal. 
     
     
       18. The method of claim 1 wherein the irradiated material includes a layer of material capable of alloying with the underlying material and at least a portion of which upon irradiation combines with the underlying material to form an essentially single crystal alloy. 
     
     
       19. The method of claims 1, 2, 5, 8, 11, 13, 15 or 18 wherein the irradiating energy is selected from the group consisting of an ion beam, and electron beam, as incoherent light beam, and a laser beam. 
     
     
       20. The method of claim 19 wherein the irradiating energy is a pulsed laser beam. 
     
     
       21. The method of claim 20 wherein the pulse period is less than one millisecond. 
     
     
       22. The method of claim 21 wherein the pulse period is less than one microsecond. 
     
     
       23. The method of claim 22 wherein the pulse period is less than one nanosecond.